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Information systems that employ synthetic speech are emerging daily in the consumer market. However, many of these systems are being developed without first investigating the numerous factors that affect the design and usability of these systems. This study investigated the effects of 16 variables on a telephone information system which uses synthetic speech as the display modality. The information system was for a fictitious department store. Subjects telephoned the system and searched for information messages on specific store items. Upon hearing the message, subjects transcribed what they heard and rated their perceived difficulty in understanding the message, their confidence in correctly remembering the message, and their perceived difficulty in finding the store item in the system. Subject search performance measures were recorded during each search, and system evaluation subjective ratings were collected at the end of each experimental session. A Hadamard 32x32 matrix design was used in this screening study to test efficiently the main effects of the 16 variables on 23 measures of user performance. Only 32 data points were required to evaluate the variables in the screening study. The analyses identified 8 variables (speech rate, menu organization, number of targets, wallet guide, menu feedback, background music, subject age, and subject gender) as having a significant effect in at least two tests; 4 variables (voice type, pause/resume, repeat keyword, and command feedback) as having a significant effect in one test; and 4 variables (input timeout, system response time, selection feedback, and spell-out keyword) that did not have a significant effect in any test. The analyses also assessed the worth of the 12 dependent measures in providing meaningful test results. / Master of Science

This thesis describes a two part research program in which the applicability of subjective ratings to the selection of independent variables was evaluated. The first portion of the research reviewed a case study involving the application of complex system investigation to the development of a telephone inquiry system. A telephone inquiry system is one in which users seek information in a data base by calling the system, listening to information presented by a synthetic voice, and directing movement through the database with commands on the telephone keypad keys. The complex system investigation method used included identifying the independent variables by brainstorming, then reducing the list by subjecting the variables to literature review, feasibility analysis, relevance analysis, and subjective ratings of the factors based on a prototype system. Variables which were not likely to have an immediate impact on human performance in the system were set to a constant value. The use of subjective ratings to select independent variables stems from the need to reduce large numbers of independent variables to a list which can be used as candidates for a screening study. The result of the case study was a list of 19 candidate factors suggested for implementation in a screening study. The second portion of the research describes an experiment in which 5 independent variables ( number of steps in a search, adapting speech rate, transaction summary, native/non-native, and sex of the voice) were chosen to represent the 19 candidate factors in an experiment testing the validity of the ·subjective ratings technique. The results indicated that the subjective ratings of the prototype system were effective in predicting performance and subjective ratings. The impact of these results on the methodology and telephone inquiry systems is also discussed. / M.S.

This paper presents a means of modulating timbre in digital sound synthesis using additive processes . A major portion of the paper is a computer program, written in Pl/1, which combines this additive method of timbre modulation with several other sound manipulation ideas to form a compositional program. This program-which is named CART for Computer Aided Rotational Translation-provides input for the Music 360 digital sound synthesis program. The paper contains three major parts: (1) a discussion of the CART program's evolution; (2) a manual describing in detail the use of CART; and (3) two tape compositions realized using the program. An appendix contains the program listing and listing of the input cards that were used to produce the two compositions.

The objective of this dissertation research is to identify sounds that grab a listener's attention. These sounds that draw a person's attention are sounds that are considered salient. The focus here will be on investigating the role of saliency in the auditory attentional process. In order to identify these salient sounds, we have developed a computational auditory saliency model inspired by our understanding of the human auditory system and auditory perception. By identifying salient sounds we can obtain a better understanding of how sounds are processed by the auditory system, and in particular, the key features contributing to sound salience. Additionally, studying the salience of different auditory stimuli can lead to improvements in the performance of current computational models in several different areas, by making use of the information obtained about what stands out perceptually to observers in a particular scene. Auditory saliency also helps to rapidly sort the information present in a complex auditory scene. Since our resources are finite, not all information can be processed equally. We must, therefore, be able to quickly determine the importance of different objects in a scene. Additionally, an immediate response or decision may be required. In order to respond, the observer needs to know the key elements of the scene. The issue of saliency is closely related to many different areas, including scene analysis. The thesis provides a comprehensive look at auditory saliency. It explores the advantages and limitations of using auditory saliency models through different experiments and presents a general computational auditory saliency model that can be used for various applications.

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The sustained increase in computing performance over the last decades has brought enough computing power to perform significant audio processing in affordable personal computers. Following this revolution, we have witnessed a series of improvements in sound transformation techniques and the introduction of numerous digital audio effects to modify effectively the time, pitch, and loudness dimensions of audio signals. Due to the complex and multi-dimensional nature of timbre however, it is significantly more difficult to achieve meaningful and convincing qualitative transformations. The tools currently available for timbre modifications (e.g. equalizers) do not operate along perceptually meaningful axes of singing voice timbre (e.g. breathiness, roughness, etc.) resulting in a transformation control problem. One of the goals of this work is to examine more intuitive procedures to achieve high-fidelity qualitative transformations explicitly controlling certain dimensions of singing voice timbre. Quantitative measurements (i.e. voice timbre descriptors) are introduced and used as high-level controls in an adaptive processing system dependent on the characteristics observed in the input signal. / The transformation methods use a harmonic plus noise representation from which voice timbre descriptors are derived. This higher-level representation, closer to our perception of voice timbre, offers more intuitive controls over timbre transformations. The topics of parametric voice modeling and timbre descriptor computation are first introduced, followed by a study of the acoustical impacts of voice breathiness variations. A timbre transformation system operating specifically on the singing voice quality is then introduced with accompanying software implementations, including an example digital audio effect for the control and modification of the breathiness quality on normal voices.

This thesis describes the construction, form, purpose and motivation for LogoRhythms, a sound synthesis and computer audition API intended to be used as a tool in the teaching of computer programming, computer science and associated skills. LogoRhythms is built into Berkeley Logo (UCB Logo), a contemporary open source Logo interpretter. In addition to serving as a user manual complete with program description and code examples, this work documents an exercise in experimental archaeology that traces the unfortunate shift in educational computing and personal computing in general from an emphasis of 'computer literacy' to one of 'user-friendly.' Arguments in defense of command-line and text based computing parallel those for computing as a tool for creative expression and are made in three ways: historical analysis, a new user-study and philosophical investigation. Programming is a widely learnable skill and debugging a useful skill transcending a utility limited to computer programs. Digital musical composition provides a perpetually renewable Opportunity for custom software, underscoring that programming is a creative endeavor.

This thesis describes the design and use of two novel digital musical instruments (DMIs) based on moving mechanical systems. The motivation behind using mechanical devices was threefold: to explore the effect of physical effort on DMIs, to make use of the device's inherent haptic and visual feedback, and to serve as a starting point for sound mappings. It was hoped that their mechanical nature would give the instruments a character that could emerge through each of the mappings. The first DMI built was the Gyrotyre, a hand-held DMI based around a small bicycle wheel outfitted with sensors that measure its speed of rotation and as well as its angle of orientation. The second DMI built was the Springwave, which consists of a loose metal spring stretched to one meter and fixed at both ends to a metal frame. The frame is in turn mounted horizontally on a hi-hat stand so that it can be raised and lowered with the pedal, thus inducing oscillation in the spring. Various mappings were designed to reflect and make use of the physical nature of both instruments. It was found that the nature of interaction with each instrument was very different depending on the mapping used. The use of mechanical devices was found to be a useful starting point for the development of mappings, and made playing the instruments engaging for the performer by the relationship between DMIs and musical contexts, a framework for characterizing DMIs that takes musical context into account is presented.